An example of a conventionally used technique is shown in FIG. 1. A base tube (base material portion) 1 according to prior art comprises a porous tube composed of 30.0 wt. % of CaO and 70.0 wt. % of ZrO2. On the surface of the base tube (base material portion) 1, there are laminated a 100 xcexcm thick fuel electrode-side electrode 2 comprising Ni-zirconia thermit, a 100 xcexcm thick electrolyte 3 comprising yttrium-stabilized zirconia (xe2x80x9cYSZxe2x80x9d), and a 100 xcexcm thick air-side electrode 4 comprising LaMnO3 doped with Sr in a proportion of 0.1. Further, a conductive connecting material 5 comprising LaCrO3 is laminated for connecting the fuel electrode-side electrode 2 with the air-side electrode 4 to form a solid oxide fuel cell (xe2x80x9cSOFCxe2x80x9d); hereinafter referred to as xe2x80x9ca fuel cellxe2x80x9d; multiple fuel cells are connected to form a device hereinafter referred to as a xe2x80x9cfuel batteryxe2x80x9d.
However, the base tube according to the earlier technology poses the problem of degrading markedly at a fast temperature raising and lowering rates during a heat cycle. In detail, with a temperature raising and lowering rate of not higher than 50xc2x0 C./hour, the performance of the cell after the heat cycle does not differ from its performance before the heat cycle. At a temperature raising and lowering rate in excess of 50xc2x0 C./hour, on the other hand, an output drop of about 10% may occur per heat cycle. When fuel cells are used as a gathering, a temperature raising and lowering rate, if not made very slow, exceeds 50xc2x0 C./hour in a part of the fuel cell gathering, thereby damaging the cell. Thus, there is a demand for a cell which is not damaged even at a high temperature raising and lowering rate of about 200xc2x0 C./hour.